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Bob McDavitt's ideas for sailing weather around the South pacific

30 October 2016

Bob Blog 30 oct

WEATHERGRAM
YOTREPS
Compiled 30 October2016
Bob McDavitt's ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the
patterned world.

The Tropics
A reminder that the NOMINAL South Pacific cyclone season starts on Tuesday.
Nothing expected this week.

After a few busy weeks, the tropics seem to be taking a rest for now. There are
a few small tropical lows around but nothing of much significance tonight.

Rain for the past fortnight from
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif
shows that last week looks similar to the previous week, except for less rain
last week in the ITCZ and the North Atlantic (than previous week).

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ this week is expected to go thru a venting process and send an bundle of
wet tropical air across Fiji tonight and across Tonga on Monday then off to the
southeast as a Low. There may be squally showers in this, so avoid departure
from Tonga on Monday. After that the zone should be reasonably quiet for the
remainder of the week.
Tropical accumulated rainfall for next week may be seen at windyty.com

Subtropical ridge (STR)
A HIGH is travelling east across central NZ on Monday-this is typical of a
summer pattern, but wrong month, so may bring some frosts, unwelcome in
vineyards at this stage.
Next high is likely to cross Tasman sea along 35S from Tuesday to Thursday and
fade west of NZ.
From Thursday onwards there should be a weak ridge along 30 to 35S across the
whole South Pacific.
Not strong enough this week to produce any squash zones.

Travel from Tahiti to Tonga:
Avoid departing from Tahiti area on local 1 to 2 Nov due light winds and a weak
passing trough. Winds looks OK for getting to Tonga, but there may be a trough
in the Tongan area early next week (7/8 Nov) so avoid that for arrival.
==============================
This is the time of year that yachts are staging themselves in Tonga (or Fiji or
New Caledonia) and waiting for the right weather pattern for sailing to NZ or
Australia.
The Island Cruising Association are supporting the All Points Rally, from all
major parts of South Pacific to Opua ending in a one-week seminar 16 to 20
November in Opua. Boats joining the rally are assisted with weather info,
resources and planning tools to help make the passage to NZ as easy as possible.
On arrival participants are welcomed to Opua and entertained with a week of
entertainment and seminars on a range of topics. This rally is FREE thanks to
the assistance of Main Sponsors Bay of Islands Marina and Boatyard and the Opua
business community. See www.islandcruising.co.nz/?page_id=717
Further west there is the GO WEST Rally. Again from any port (most are leaving
from Noumea) this time to BUNDABERG, with welcome week starting 6 November 2016.

See www.downunderrally.com/westrallyfee
==============================
Travel between Tonga and NZ:
South Pacific convergence zone or maybe an upper trough expected to cross Tongan
area on Monday= possible squally showers, southerly winds gusty and lightning.
May as well stay put for that.
Remainder of week looks OK for departure; the next rough is expected early next
week.
The arrival times to avoid getting S of 30S to NZ are Mon to Wed 7 to 9 Nov.

Travel between Fiji and NZ
Diwali Public holiday on Monday
South Pacific convergence zone or maybe an upper trough should clear off by
Tuesday morning then OK to depart for remainder of the week.
The arrival times to avoid getting S of 30S to NZ are Mon to Wed 7 to 9 Nov.

Travel between New Caledonia and NZ
Public holidays on Monday and Tuesday (All Saints) so can't check out until
Wednesday,
Weather traffic along the way -there's a mediocre trough on Tue/wed 1/2 Nov,
then a weak low on Fri/sun 4/6 Nov, Avoid getting south of 30S Mon to Wed 7
to 9 Nov.

Travel for New Caledonia to Australia
Public holidays on Monday and Tuesday (All Saints) so can't check out until
Wednesday,
A trip to Bundaberg goes through a passing mediocre trough, no strong winds but
a period of variable winds to challenge you.
Going to NSW, the weather traffic along the way is the challenge of active cold
front on Sat 5 Nov followed by strong to gale southerly winds and rough seas,
and a trough off Coffs on Fri 11 Nov.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Follow me on Facebook at www.facebook.com/metbobnz/
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts-
Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
Weathergram text only (and translator) is at weathergram.blogspot.co.nz.
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Click FOLLOW at bottom right to subscribe.
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23 October 2016

Bob Blog 23 Oct 2016

WEATHERGRAM
YOTREPS
Compiled 23 October2016

Bob McDavitt's ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the
patterned world.

TROPICAL CYCLONE SEASON OUTLOOK
The South Pacific/Australian tropical cyclone season is from nominally from 1
Nov to 30 April. A neutral to weak or moderate LA NINA is expected to affect the
tropical Pacific Ocean over the next six months. This tends to nudge the South
pacific convergence zone to the south and west of its normal position,
increasing the cyclone risk around Australia and Coral Sea, and perhaps reducing
this risk in places east of the dateline.
The Bureau of Meteorology have considered this and say that the cyclone risk
over Northern Australia is increased. The average number of cyclones per season
across the entire region is 11.
See more at www.bom.gov.au/climate/cyclones/australia/

Looking at the behaviour of the sea surface temperature over the past year, NIWA
has searched the database for analogue years that may point the way as to how
this season may develop. The top analogues are 1969/70; 1983/84; 1992/93;
1995/96; 2005/06; 2010/11 and using this data they have compiled a cyclone risk
map, as
at www.niwa.co.nz/news/southwest-pacific-tropical-cyclone-outlook
They have applied these risks to the average occurrence of tropical cyclones to
come up with a map showing likely numbers of TC in each sub area this season.
See www.niwa.co.nz/news/southwest-pacific-tropical-cyclone-outlook
The average number of cyclones across the South Pacific region per season is
12.4 cyclones.

TROPICS
Philippines got a double hit last week from TC SARIKA (KAREN in the Philippines)
and HAIMA (LAWIN in the Philippines).
NASA have produced a video showing the resulting extreme accumulated rainfall at
www.eurekalert.org/pub_releases/2016-10/nsfc-nme102116.php

At present there are two tropical depressions that are being forecast by the
computer models to become cyclones this week (one in Northern India Ocean and
one west of Mexico), and there possible fture tracks are seen at
ruc.noaa.gov/tracks/

Rain accumulation maps show the two cyclone tracks over the Philippines, and the
track of NICOLE in the Atlantic, and a rebuild of the South Pacific Convergence
Zone.
These may be seen at
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif

WEATHER ZONES

This is the time of year that yachts are staging themselves in Tonga (or Fiji or
New Caledonia) and waiting for the right weather pattern for sailing to NZ or
Australia.

The Island Cruising Association are supporting the All Points Rally, from all
major parts of South Pacific to Opua ending in a one-week seminar 16 to 20
November in Opua. Boats joining the rally are assisted with weather info,
resources and planning tools to help make the passage to NZ as easy as possible.
On arrival participants are welcomed to Opua and entertained with a week of
entertainment and seminars on a range of topics. This rally is FREE thanks to
the assistance of Main Sponsors Bay of Islands Marina and Boatyard and the Opua
business community. See www.islandcruising.co.nz/?page_id=717

Further west there is the GO WEST Rally. Again from any port (most are leaving
from Noumea) this time to BUNDABERG, with welcome week starting 6 November 2016.
See www.downunderrally.com/westrallyfee

Travel between Fiji/Tonga and NZ:
The next trough to affect Fiji is expected on 29 /30 Oct an winds should return
to SE on 1 Nov. For Tonga that trough is expected 31 oct/1 Nov wit winds
returning to S/Se on 2 Nov. Avoid departing during this trough.
There are expected to be large slow-moving highs crossing between Tonga/Fiji and
NZ this week, so try and go around the back end of these highs to avoid their
light winds (unless motoring). The highs are NOT expected to be intense enough
to form squash zones between Tonga/Fiji and NZ, but may be some in the Coral
Sea.
Try and avoid arriving at NZ when a trough passes Northern NZ on Tue night/ Wed
1/2 Nov.

Travel between New Caledonia and Brisbane/Bundaberg area:
That weekend surcharge is a factor to consider. As for departing from Noumea,
well there are only light winds forecast for local Monday and Tuesday, so that
makes Wednesday onwards the best days to depart this week. The next trough to
reach Bundaberg is expected on 31 Oct but really that trough is further south,
so that's when Bundaberg may have light variable winds.

Travel from New Caledonia to New South Wales
No real point in taking the rhumb line for such a voyage as the subtropical
ridge should be gone around rather than thru. Instead head for Brisbane, and
around 158E turn to your destination. This should also give you the benefit of
the assistance of the East Aussie current. However, note that there is an active
trough south of 30S on Monday 31 Oct/Tue 1 Nov.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Follow me on Facebook at www.facebook.com/metbobnz/
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts
Feedback is to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
Weathergram text only (and translator) is at weathergram.blogspot.co.nz.
Weathergram with graphics is at metbob.wordpress.com,
Click FOLLOW at bottom right to subscribe.
To unsubscribe send a reply email saying LEAVE.

16 October 2016

Bob blog 16 Oct

WEATHERGRAM
YOTREPS
Compiled 16 October2016
Bob McDavitt's ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the
patterned world.

FLEET CODE
Regarding the notes I wrote last week about FLEET code, Chuck on JACARANDA has
replied as follows:
>>>>>
We use two methods to view it
Physplot - The easiest way to use this is to just drag the unopened email right
onto the fleetcode icon on our desktop. It automatically opens and loads.
(This is using sailmail)
By sliding the viewing screen slightly to the right the actual text appears and
you can read about what you are seeing on the screen.

OpenCPN
We prefer this as it gives us greater visibility of the overall area. You can
download the fleet code plug in from opencpn.org website.
>>>>>
When referring to the Fiji Day LOW last Monday I noticed that the upper trough
responsible was also shifting a "Vorticity max" out of the Tasman Sea and onto
Vanuatu. See my Facebook post at www.facebook.com/metbobnz/
An upper trough penetrates the South Pacific convergence zone over Fiji on 10
Oct, causing winds to spin and spiral downwards forming a surface low over
Fiji=The Fiji Day low. The extra upward motion brought heaps of RAIN. and as a
sideline, an entity of the west side of the upper trough known as a Vorticity
Max is taken by the southwest winds aloft from the Tasman Sea onto New Caledonia
then onto Vanuatu.
Well, A village just north of Port Vila (Tongamea) had a significant HAIL STORM
as a consequence.
I received photos of this hail from my good friend Alex from Honiara Weather
Office.
===========
We are having a full moon this weekend, and so next weekend is the start of the
last quarter of the waning moon. That's when the full tide is overnight, and
it's the first of these events after the equinox that triggers the season for
PALOLO. when the coral worms spawn. They drop off their worm-tails or pods; jade
(female) or brown (male); and these mix together in the swirling tide, with each
having a light sensitive spot that directs it towards the moon as it sinks in
the west (or to a flashlight). At dawn the pods dissolve, allowing eggs and
sperm to get together and start the new generation. The rising is only on the
turn of that one tide and only takes place for a few hours. Samoan Met Office
say Oct 22/23 is this year's best chance.
Ask the locals about this and if you time it right you may be about to collect
some of this rare delicacy, or photo it. They might look yucky, but taste really
nice on toast, something like caviar, so I'm told.
=======
TROPICS
Bureau of Met and NIWA have both issued their cyclone forecast for the coming
season in the past few days-I'll cover that next week for you.
======
In the NW Pacific tonight we have TC SARIKA and HAIMA, see them at
ruc.noaa.gov/tracks/
And in the Atlantic, after a very destructive path last week from MATTHEW, we
have NICOLE keeping well offshore, but making a direct hit over Bermuda as a Cat
3 (Saffir-Simpson scale). The radar image of this can be seen at
www.wunderground.com/blog/JeffMasters/

Rain for the past fortnight (from
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif) show an increase
in convection over Philippines, the track of MATTHEW and NICOLE in the Atlantic,
and a burst of rain over Fiji thanks to the Fiji Day low, but a removal of
convection from Solomons as a consequence.

WEATHER ZONES
Tropical accumulated rainfall for next week can be seen at windyty.com

Tropics to NZ/ Australia: - Strategy
This is the time of year that yachts are staging themselves in Tonga (or Fiji
or New Caledonia) and waiting for the right weather pattern for sailing to NZ or
Australia.

The Island Cruising Association are supporting the All Points Rally, from all
major parts of South Pacific to Opua ending in a one-week seminar 16 to 20
November in Opua. Boats joining the rally are assisted with weather info,
resources and planning tools to help make the passage to NZ as easy as possible.
On arrival participants are welcomed to Opua and entertained with a week of fun
and games, entertainment and seminars on a range of topics. This rally is FREE
thanks to the assistance of Main Sponsors Bay of Islands Marina and Boatyard and
the Opua business community. See www.islandcruising.co.nz/?page_id=717

Further west there is the GO WEST Rally. Again from any port (most are leaving
from Noumea) this time to BUNDABERG, with welcome week starting 6 November 2016.
See www.downunderrally.com/westrallyfee

In deciding upon a departure date, it's as simple as 1.2.3:

1.The first factor to consider is the local weather: the South Pacific
Convergence Zone SPCZ sometimes brings squalls, but is well to the north this
week and still recovering after being vented by the Fiji day Low last Monday.
However, we have a passing (mainly upper) trough over Fiji on Monday/Tuesday,
and this trough is expected to slowly cross Tonga area on Tuesday/Wednesday.
This trough is likely to bring squalls and maybe some strong SE winds, so better
to wait for it to go before departing.
Some like to use Minerva reef as an extra staging post since it is 1.5 to 2 days
sail south of Tonga, and just out of the tropics (so marine insurance that may
be void in the tropics may work in Minerva). But it only shelters you from the
waves (so long as they don't topple over the reef) and not from the wind or
rain. It has that passing trough on Tuesday (local) with some rain until
Thursday, and is only likely to have fresh easterly winds form this feature.

2.The second factor to watch are the HIGHS that travel along the Subtopic ridge
STR, that zone between the trade winds of the tropics and the disturbed
westerlies of the roaring 40s. This zone is usually near 30S, and if there is a
big high then on its northern side there is usually an accompanying are of
enhanced trade winds, what I call a SQUASH ZONE. This week there is a HIGH
moving along 30S from N Tasman Sea tonight to east of NZ on Wednesday, and there
is a squash zone between that High and the trough over Tonga, mainly on
Wednesday/Thursday. The next High should start further south and cross the
Tasman Sea from Thursday to north of NZ on Sat 22 Oct, without any squash zone.

3.The third factor is to avoid bursts of strong southerly winds and heavy swells
during the trip or upon arrival. These come from the Southern Ocean and on a
different pattern to the passing troughs in the tropics. Sometimes a southerly
burst inter-reacts with a tropical trough and things get nasty. Not this week.
You can use windyty.com to see expected weather features at your arrival point
for the next week, and aim to arrive "in-between active features", but remember
that these outlooks are just ideas, and real world will do its own thing. Over
northern NZ there is expected to be a weak passing trough on Thursday, and then
northern weakening trough on Sunday 23, and then maybe some strong SW winds from
a passing southern Low on Mon 24/Tues 25 Oct. And over the Australian coast
there is a passing trough this Monday and another mainly south of 30S, on
Friday, weaker further north on sat/Sun. I think you can handle these fronts
with suitable waypoints/timing.

Let's apply this 1,2,3 rule to some popular destinations:

Travel between the Tropics and NZ:
If heading from Fiji or Tonga, wait for that trough to go first. Maybe Wed from
Fiji and Thu from Tonga. but that may change. Arrange waypoints so as to
encounter that Sun 23 over NZ front near 30S. That depends on boat speed, and
configuration, so will vary from vessel to vessel.

Travel between New Caledonia and Brisbane/Bundaberg area:
Trough that was over New Caledonia yesterday has gone east now, but there is a
squash zone between it and the Tasman Sea High. That should ease during Monday.
Then OK to go anytime, but expect to encounter a weak passing trough around next
Sat/Sun as you approach coast. If you arrive over the weekend then there's a
surcharge to pay.

Travel from tropics to New South Wales
No real point in taking the rhumb line for such a voyage as the subtropical
ridge should be gone around rather than thru. Instead head for Brisbane, and
around 158E turn to your destination. This should also give you the benefit of
the assistance of the East Aussie current. However, remember that there is an
active trof south of 30S on Friday 21/Sat 22 Oct.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts-
Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
Weathergram text only (and translator) is at weathergram.blogspot.co.nz.
Weathergram with graphics is at metbob.wordpress.com,
Click FOLLOW at bottom right to subscribe.
To unsubscribe send a reply email saying LEAVE.
Follow me on Facebook at www.facebook.com/metbobnz

09 October 2016

Bobgram 9 October 2016

WEATHERGRAM
YOTREPS
Compiled 9 October2016

Bob McDavitt's ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the
patterned world.

FLEET CODE
Back when I was a boy the FLEET CODE was established allowing a weather map to
be sent to the whole Fleet all at once via Morse code transmitted over
Shortwave. In this age of readily available GRIB data (from some models) the
FLEET code has fallen off the back shelf of technology. However, the Fiji Met
Service are still manually converting their analysis map into fleet code and,
thanks to Mike Harris of Pangolin and the people at saildocs these maps can be
downloaded as email and drawn on your own computer as you travel around the
South Pacific.

They have an advantage over GRIB files in that they contain convergence zones,
as seen by Fiji Met Service meteorologists using satellite imagery to fine tune
placements.
To download the latest Nadi Fleet code send an email to query@saildocs.com, no
subject needed, saying SEND nadi-fleetcode.
When you receive the reply email, use something such as notepad to save the data
as a file and store this, say, on your desktop, as, e.g. fleet.txt
Mike Harris' PANGOLIN website contains a page which allows you to save a beta
version of PhysPlot. Go to www.pangolin.co.nz/physplot . This is a windows
program physplot.exe (now called a desktop ap) which can open that file
fleet.txt and turn it into a weather map for you.
Tonight's situation on Fleet map shows a convergence zone north of Fiji shifting
south, and a weak trough has been drawn over Fiji.

The Tropics
Tonight in the Atlantic, TV MATTHEW, after hitting Haiti hard last week, has
finished grazing the east USA coastline and is now moving east out to sea. TC
NICOLE is on the SE side of MATTHEW. See ruc.noaa.gov/tracks/

And in the Pacific TC SONGDA is likely to recurve soon, but TC AERE in the China
Sea may make landfall over Vietnam, rather an usual event.


Rain for the past fortnight as seen at
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif
shows an increase in convection Christmas Island area to NW of Australia, and in
the South Pacific, especially to north of Fiji. MATTHEW's rain-footprint stands
out clearly.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ this week is expected to congeal into a wet trough over Fiji during Monday
= Fiji Day. A Low may form over the Lau group late on Monday, bringing some
strong winds and squally rain to Tonga on Monday night and Tuesday. Avoid.
This Fijian trough is expected to spread westwards, so that a zone of LIGHT
WINDS is expected over western Fiji to Vanuatu. Not good for sailing.
So the South Pacific convergence zone this week goes thru a period of
intensification, then congealment (over Fiji) and then a venting of its energy
off to the southeast. This pattern is consistent with the arrival of an MJO
(Madden Julian Oscialltion) in the South Pacific , as seen at
www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_mjo_index/mjo_index.html
When the blue shaded area in this MJO time/latitude cross section enters the
South Pacific we tend to see tropical lows. Note that these MJO arrivals occur
once every 4 to 8 weeks at this time of year, but may be more regular during the
coming cyclone season. Worth watching.

Subtropical ridge (STR)
This is expected to remain weak and further north than normal along round 25S
between Australian coast and 180. Further east it should spread south. No squash
zone this week.

Travel from Tahiti to Tonga:
Winds may be Ok for a departure on local Sunday, then just light winds are
expected over Tahiti area until next week,

Travel between the Tropics and NZ:
Light winds over western Fiji and Vanuatu area this week, so maybe stay put and
wait for trade wins to return.
There is a Low affecting Tongan area on Monday/Tuesday, then light variable
winds for the remainder of the week. So maybe wait for something better.
If you are already on your way to NZ then be mind-fall that a LOW from Tasman
sea is likely reach northern NZ around Sun 16/Monday 17, and another maybe
around Thu 20/Fri 21 Oct. try and avoid these dates for arrival, but these are
provisional and may change, so also seek an update.

Travel between New Caledonia and Brisbane area:
Weak trough is expected to cross Brisbane area on Tue 11 Oct. followed by a few
days with southerly winds. This trough should spread east reaching New Caledonia
around Sat 15 Oct and then lingering there until Sunday 16 Oct
No strong winds expected with this trough so maybe Ok to sail thru it, but not
100%.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts-
Feedback to bob@metbob.com.
Tell anyone you like that to subscribe they should email me.
Weathergram text only (and translator) is at weathergram.blogspot.co.nz.
Weathergram with graphics is at metbob.wordpress.com,
Click FOLLOW at bottom right to subscribe.
To unsubscribe send a reply email saying LEAVE.

06 October 2016

Fiji Day tropical Low

FIJI DAY Tropical Low
The GFS model persists in picking that a tropical low may form on Fiji Day Mon
10 Oct and then deepen as it travels SE across Tonga

This could bring brief strong to gale winds to Tonga on Tuesday 11 Oct. But
other models still come up with different scenarios, and, of course, the real
world will do its own thing.

Listening to warnings that are now being issued as TC MATTHEW heads to Florida,
I am reminded that we should hope for the best, but prepare for the worst. And
so when the models differ from each other, as they do in today's run for early
next week, we need good tools so that we can see the difference.

One good tool I recommend in such cases is www.tropical
tidbits.com/analysis/models
Select the Southwestern pacific region and it defaults to GFS models and you can
click thru to 12Z Mon 10 Oct= midnight end of Monday Fiji time/1am Tuesday
Tongan & NZ time. This looks yucky for Tonga.
Then the website allows you to click GLOBAL (models) and switch to ECMWF, it
keeps the same timestamp.
Or CMC (the other two options, NAVGEM and JMC, don't work in the Southwestern
Pacific region).

This quickly shows you the difference between the models, and that in itself is
a helpful step. As to trying to surmise what may happen in the real world, well
that takes skill and experience, and is a job for meteorologists. My pick is
the Low may actually be placed SW of Tonga on Tuesday, sort a merger of the
above models.

A similar tool is provided by windyty.com, which can flick between EC and GFS
models.

Also Predictwind.com offers a side-by-side page comparing itt PWG and PWC
models, but this may require a subscription.



Cheers from Bob

02 October 2016

Bob Blog 2 Oct 2016

WEATHERGRAM
YOTREPS
Compiled 2 October2016

Bob McDavitt's ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the
patterned world.

SEPTEMBER was an interesting month.
September averaged isobars may be seen at
www.esrl.noaa.gov/psd/map/images/fnl/slp_30.fnl.anim.html
Pressure anomalies seen at
www.esrl.noaa.gov/psd/map/images/fnl/slp_30a.fnl.anim.html show that
for much of September HIGHS lingered south and east of NZ.
A time-longitude cross section of the blocking index shows this blocking was
strongest between 6 and 11 September.
See
www.cpc.ncep.noaa.gov/products/precip/CWlink/blocking/real_time_sh/real_time_ind
ex_nrm.shtml

The lingering highs in this area led to more NE winds onto eastern parts of the
North Island, so that by the end of the month some parts of Coromandel had an
accumulated rainfall around a metre --- an amount more typical of Fjordland.
Topsy-turvy weather.

The Tropics
Tonight TC MATTHEW is Cat 5 as it moves to the Jamaica /Haiti/ Cuba area.
May be seen at ruc.noaa.gov/tracks/
And in the NW Pacific TC CHABA is moving towards Japan.

Rain for the past fortnight may be seen at
trmm.gsfc.nasa.gov/trmm_rain/Events/big_global_accumlation.gif
Rain accumulation maps show an increase in convection over Indonesia and
Philippines and along the Intertropical Convergence zone across the central
Pacific, and to north of South America. Also a decline in activity in the North
Atlantic and Tasman Sea. The front that knocked the power out over South
Australia last Thursday shows up well.

WEATHER ZONES
SPCZ=South Pacific Convergence zone.
SPCZ this week is expected to remain much the same in the Solomon Islands to
Tokelau area, with another finger covering northern Vanuatu and the sea between
Vanuatu and Fiji. Another branch of the SPCZ may cover the zone from Niue to
Gamier Islands in a loose and scattered manner.
A tropical LOW is expected to form in the Vanuatu to Fiji area on Sun 9/Mon 10
Oct and then MAY go SE across Fiji on Fiji day holiday on Mon 10 Oct-to Thu 13
Oct, consider avoiding.

Subtropical ridge (STR)
This is expected to remain weak and further north than normal along round 25S
between Australian coast and south of French Polynesia. It is likely to get
wider and stronger from this weekend and stretch to 30S.

Travel from Tahiti to Tonga:
Light winds over Tahiti area until local Tuesday. Then winds may be Ok for
getting as far west as Niue. As for Tonga, well, a passing trough associated
with the Fiji Low is expected around Mon 10/Tue 11 Oct local. Avoid.

Travel between the Tropics and NZ:
A trough is expected to bring strong winds and showers to northern NZ on Tuesday
night and another more intense trough is expected to bring strong winds to
northern NZ on Thursday /Friday followed by SW swells from the Southern Ocean
over 4 metres reaching as far north as 22S on Friday might/Saturday NZ time.
Peak swells are likely to be over 8 metres near northern NZ on Thu night/Fri 7
Oct. Avoid.

Travel between New Caledonia and Brisbane area:
A ridge is expected to travel along 25/30S across Tasman Sea from Thu night 6
Oct and to get east of NZ from Mon 10 Oct. This should provide good conditions
for sailing from Fiji to New Caledonia or from New Caledonia to Brisbane, but
NOT for going east.
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See my yotpak at boatbooks.co.nz/weather.html for terms used.
See my website www.metbob.com for information on tailor-made voyage forecasts
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